pm.system.sceneName() sometimes gives empty string


Hello there.
I have a python script which does things, and in this script i want to get the scene name by using the pm.system.sceneName() function. But sometimes it only returns an empty string. What causes this and how can i make sure that i always retrieve the scene name?


Solved it (i think).
If the maya scene is not saved the string is empty, by saving the scene and restarting maya the sceneName returns the correct string